Re: [PATCH v3 2/3] shared memory: Define PCI capability

[Stefan Hajnoczi <stefanha@redhat.com>]

On Thu, Mar 07, 2019 at 06:24:57PM +0000, Dr. David Alan Gilbert wrote:
> * Stefan Hajnoczi (stefanha@redhat.com) wrote:
> > On Mon, Mar 04, 2019 at 01:25:30PM +0000, Dr. David Alan Gilbert (git) wrote:
> > > +\begin{lstlisting}
> > > +struct virtio_pci_shm_cap {
> > > +        struct virtio_pci_cap cap;
> > > +        u32 offset_hi;
> > > +        u32 length_hi;
> > > +        u8  id;
> > > +};
> > > +\end{lstlisting}
> > 
> > Are there any alignment requirements for PCI capability structures?
> 
> The PCI spec says 'Each capability must be DWORD aligned. '
> 
> > This struct ends with a u8, which might be a problem if 32-bit or 64-bit
> > alignemnt is required by something.
> 
> It doesn't seem to be unusual, for example the MSI capability structure
> seems to be 10 or 14 bytes even with the DWORD alignement restriction
> for the start of it.

Sounds good.  Just wanted to check.

Stefan

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